A tax inversion is a corporate merger strategy that involves a company based in one country, say the U.S., acquiring another company based somewhere else, say the U.K., and following the deal moves its tax base to enjoy a lower corporate tax rate.

This year, some notable tax inversions, or proposed tax inversions, include Minnesota-based Medtronic's $43 billion deal to acquire Covidien and move its tax base to Ireland; Illinois-based AbbVie's $53 billion deal to acquire Shire and move its tax base to Jersey, an island in the English Channel; and New York-based Pfizer's failed attempt to acquire U.K.-based AstraZeneca.

Pfizer's deal to acquire AstraZeneca, which was withdrawn in May, would've been the biggest of these mergers, with the deal totaling $120 billion.

A report in The New York Times this morning said that the Obama administration is continuing to push for legislation that could retroactively strip the tax advantages achieved by companies in some of this year's deals.

And so it seems that both Congress and Wall Street have taken notice of this loophole, and one look at this chart from Goldman Sachs says it all.